The invention relates to a memory cell that operates by storing charge; in preferred embodiments, two bits are stored per cell, the cell programmed by a channel hot electron injection method.
As will be described, using a channel hot electron injection method, charge can selectively be stored in neither, either, or both of two distinct charge storage regions in a transistor-based memory cell, increasing device density by storing two bits per cell. As the cell is formed at smaller feature size, however, it becomes increasingly difficult to keep the two storage regions distinct.
There is a need, therefore, for a high-density charge storage memory cell in which two separate charge storage regions are kept distinct without increasing the area of the cell.